JPH10246729A - Minute tip and probe using the same for detecting minute current or minute force, and their manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a minute tip of a uniform shape with less abrasion and good reproducibility, by forming the minute tip of a metal and forming a metallic oxide on a surface of the tip. SOLUTION: A protecting layer 2 is formed on a silicon first substrate 1. A recessed part 3 is formed at a part of the protecting layer 2 by anisotropic etching. The protecting layer 2 is removed, and a separation layer 4 is formed. A tip chief material 51 of a minute tip 6 is formed of a conductive metal such as Al, Ti, Cr or the like in a film on the separation layer 4 including the recessed part 3. A bonding auxiliary layer 52 and a separation auxiliary layer 53 are formed of Au on the chief material 51. A bonding layer 7 is formed on a second substrate 8 or an elastic body formed on the second substrate. The minute tip 5 on the separation layer 4 is bonded to the bonding layer 7. The separation layer 4 and the minute tip 5 are separated, and the minute tip 5 is transferred onto the bonding layer 7. The separation auxiliary layer 53 is removed. The tip chief material 51 is heated in the atmosphere or an ambiance of oxygen, so that a surface of the tip chief material 51 is oxidized and a surface oxidation film 54 is formed. Accordingly to this method, a uniform shape of good reproducibility is obtained without requiring application of conductivity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a micro tip (probe) used in a scanning tunneling current microscope or an atomic force microscope for detecting a micro force, a probe having the tip, and a method of manufacturing these. It is about.

[0002]

2. Description of the Related Art In recent years, a scanning tunneling microscope (hereinafter referred to as ST) capable of directly observing the electronic structure of surface atoms of a conductor.
M) (G. Binnig et a).
l. Phys. Rev .. Lett, 49, 57 (19
82)), real space images can be measured with high resolution irrespective of single crystal or amorphous. In addition, it has the advantage that it can be observed at low power without damaging the sample due to electric current, and since it can operate in the atmosphere and can be used for various materials, its widespread application is expected in the future. Such an STM utilizes the fact that a tunnel current flows when a voltage is applied between a metal tip and a conductive material to approach a distance of about 1 nm. Since this current is very sensitive to the change in distance between the two and changes exponentially, the surface structure in real space is observed with atomic-level resolution by scanning the tip so that the tunnel current is kept constant. be able to. The object of analysis using this STM has been limited to conductive materials, but has also begun to be applied to structural analysis of an insulating layer formed thin on the surface of the conductive material. Further, since the above-described apparatus and means use a method for detecting a small current, there is an advantage that the medium can be observed without damaging the medium and with low power. In addition, since operation in the atmosphere is also possible, observation and evaluation of atomic order and molecular order of semiconductors or polymer materials, and fine processing (EE Ehrichs, Proc.
eatings of 4th International
nal Conference on Scannin
g tunneling Microscopic / S
Spectroscopy, "89, S13-3) and its application to various fields such as information recording / reproducing devices, etc. Further, according to an atomic force microscope (hereinafter, abbreviated as AFM), it acts on the surface of a substance. In order to detect repulsive and attractive forces, it is possible to measure an uneven image of the sample surface regardless of the conductor or insulator, and this AFM uses a cantilever with a small tip formed at a free end. A probe with the functions of AFM and STM at the same time is manufactured by imparting conductivity to the microtip of the AFM probe, and a voltage is applied between the microtip and the sample to simultaneously obtain information on the conductivity and shape of the sample. Memory technology that changes the conductivity of a recording medium by contacting the microtip with the recording medium and applying a voltage between the microtip and the recording medium Etc. have been developed.

As shown in FIG. 8A, a method for manufacturing a microtip used in the probe is, for example, that a thin film layer 202 on a substrate 201 is patterned into a circle and the substrate 201 is etched using the pattern as a mask. Then, a method of forming the tip 203 using side etching (O. Wolter, et al., “Microm
attached silicon sensors f
or scanning force microsc
opy ", J. Vac. Sci. Technol. B9.
(2), Mar / Apr, 1991, pp1353-1
357), and as shown in FIG. 8B, the resist opening 206 of the resist 205 having a reverse taper.
The conductive material 207 is obliquely deposited while rotating the substrate 204, and lifted off to form a tip 208.
A method proposed by Spindt and others (CA Spindt, et al., "Ph.
ysical properties of thin
film fielddemitation catho
de with molebdenum cones "
J. Appl. Phys. , 47.1976, pp52
48-5263). Further, a micro tip formed by anisotropic etching using single crystal silicon by using a semiconductor manufacturing process technique is known (US Pat. No. 5,221,415). As shown in FIG. 9, the method for forming the fine tip is as follows.
Pits 518 are formed by anisotropic etching on the silicon wafer 514 covered with the masks 0, 512, the silicon dioxide 510, 512 is removed, and then the silicon nitride layers 520, 521 are coated on the entire surface to form a cantilever (cantilever). ) And a pyramid-shaped pit 522 to be a micro tip
After patterning into a cantilever shape, the silicon nitride 521 on the back surface is removed, and a glass plate 530 provided with a saw cut 534 and a Cr layer 532 is formed.
20 and the silicon wafer 514 are removed by etching to produce a tip and a probe made of silicon nitride transferred to the mounting block 540.

However, in the conventional example as shown in FIG. 8, a strict process is required to keep the silicon etching conditions, resist patterning conditions, conductive material deposition conditions, and the like in forming the tips constant. There is a problem that management is required, and it is difficult to maintain an accurate shape such as a height and a radius of curvature of a tip of a plurality of minute tips to be formed. In addition, in the probe as shown in FIGS. 8A and 9, when imparting conductivity, a conductive material is coated by a vacuum deposition method or a sputtering method, but agglomerates of the conductive film may be formed. There was a problem that it was difficult to control the agglomerates with good reproducibility. For this reason, a method has been developed in which a metal material is deposited on a female substrate having a concave portion obtained by anisotropically etching a silicon substrate, patterned, and transferred to an arbitrary substrate (Japanese Patent Application Laid-Open No. 06-0844455). Gazette) (see FIG. 10).
In this method, the shape of the tip is formed with good reproducibility and sharpness by anisotropic etching, and the material itself has conductivity, so there is no need to cover the conductive material, and the tip is removed without etching the female substrate. It is an excellent technology that can form

[0005]

However, the use of the probe shown in FIG. 10 has the following problems. That is, when the tip is brought into contact with the sample and scanning is performed while applying a load to the sample, the micro tip having a metal tip is easily worn out, and particularly, the metal tip is brought into contact with the metal sample. In the case of observing a clean Au surface with a fine tip made of Pt, for example, there is a problem that even when the load is 1 × 10 ⁻¹⁰ N or less, abrasion occurs due to contact scanning. Further, when a high voltage is applied between the tip and the sample (recording medium), there is a problem that the microtip having a metal tip is easily deformed by the influence of an electric field or heat.

Accordingly, the present invention is directed to FIGS.
It solves the problems of the prior art as shown in Fig. 0, and it is not necessary to impart conductivity by sputtering of a conductive material. On the other hand, the tip of the micro tip does not deform, a uniform shape with good reproducibility can be obtained, the tip can be formed sharply, and the tip can be easily multiplied (multiple). It is an object of the present invention to provide a probe for detecting a minute force and a method for manufacturing the same.

[0007]

In order to solve the above-mentioned problems, the present invention provides a micro tip, a micro current or micro force detecting probe using the micro tip, and a method of manufacturing the micro tip or probe. It is characterized by the following. That is, the microtip of the present invention includes a substrate, a bonding layer made of metal formed on the substrate, a microtip portion formed on the bonding layer, and the microtip portion surrounded by the bonding layer. In a minute tip having a hollow region, the minute tip is mainly composed of a metal, and a metal oxide is formed on a surface of the minute tip. Further, the probe of the present invention comprises a substrate, an elastic body formed on the substrate, a bonding layer made of metal formed on the elastic body, a microtip portion and the microtip on the bonding layer. A probe having a microtip for detecting a microcurrent or a microforce having a portion and a hollow region surrounded by the bonding layer, wherein the microtip has a metal as a main material and a metal oxide is formed on the surface thereof. It is characterized by being formed. In the present invention, the tip is made of a material whose main material is aluminum Al, titanium Ti, vanadium V, chromium Cr, nickel Ni, zirconium Zr, niobium Nb, molybdenum Mo, tin S
n, hafnium Hf, tantalum Ta, tungsten W,
, Or rhenium Re. The method for producing a microtip of the present invention comprises the steps of (a)
Forming a recess on the surface of the first substrate; (b) forming a release layer on the first substrate including the recess; and (c).
A step of forming a microtip mainly made of metal on the release layer including the concave portion, a step of (d) forming a bonding layer on the second substrate, and (e) a release layer including the concave portion of the first substrate Bonding the upper microtip to the bonding layer on the second substrate; and (f) separating the microtip on the bonding layer of the second substrate by separating at the interface between the release layer and the microtip. And (g) oxidizing the surface of the microtip transferred onto the bonding layer of the second substrate. In one embodiment of the step (c) in the method of manufacturing a probe of the present invention, a bonding auxiliary layer is formed on a tip main material formed on a release layer in order to securely press a microtip. It is characterized by: In another embodiment of the step (c) in the method for producing a microtip of the present invention, a peeling auxiliary layer is formed to surely peel off the microtip before forming the tip main material on the peeling layer. And the step of removing the auxiliary separation layer before the step (g). Further, in still another mode of the step (c) in the method for producing a microtip according to the present invention, a separation auxiliary layer is formed to surely release the microtip before forming the tip main material on the release layer. And forming a bonding auxiliary layer to securely press the microtip on the tip main material formed on the release layer, and removing the release auxiliary layer before the step (g). It is characterized by. Also,
Another embodiment of the method for manufacturing a microtip of the present invention is characterized in that a plurality of the concave portions are formed on a surface of the first substrate and a plurality of the microtips are formed on the second substrate. The method for manufacturing a probe for detecting a microcurrent or a microforce according to the present invention includes: (a) forming a concave portion on the surface of the first substrate; and (b) forming a release layer on the first substrate including the concave portion. (C) forming a microtip on a release layer including the concave portion; (d) forming an elastic material on a second substrate; and (e) forming an elastic material on the second substrate. Forming a bonding layer on a material; (f) bonding a microtip on a release layer including a concave portion of the first substrate to a bonding layer on the second substrate; and (g) bonding the release layer. (H) transferring the fine tip onto the bonding layer of the elastic material on the second substrate by peeling off at the interface between the elastic substrate and the fine tip; Forming a body, and (i) transferring to a bonding layer of an elastic body on the second substrate. It is characterized by having a step of oxidizing the micro-tip surfaces, at least. In one mode of the step (c) in the method of manufacturing a probe of the present invention, a bonding auxiliary layer is formed on a tip main material formed on a release layer in order to securely press a microtip. It is characterized by: In another embodiment of the step (c) in the method for producing a probe of the present invention, a peeling auxiliary layer is formed to surely peel off a microtip before forming a tip main material on a peeling layer, Further, the method is characterized in that the peeling auxiliary layer is removed before the step (i). Further, in still another mode of the step (c) in the probe manufacturing method of the present invention, a peeling auxiliary layer is formed to surely peel off a minute tip before forming a tip main material on a peeling layer. And forming a bonding auxiliary layer to securely press the microtip on the tip main material formed on the release layer, and removing the release auxiliary layer before the step (i). Features. In another aspect of the method of manufacturing a probe according to the present invention, a plurality of the concave portions are formed on the surface of the first substrate, and a plurality of the microtips are formed on the second substrate. . In the method for manufacturing a microtip or the method for manufacturing a probe according to the present invention, the tip is made of a material whose main material is aluminum Al, titanium Ti, vanadium V, chromium Cr, nickel Ni, zirconium Zr, niobium. Nb,
It is characterized by being one of molybdenum Mo, tin Sn, hafnium Hf, tantalum Ta, tungsten W, and rhenium Re.

[0008]

DETAILED DESCRIPTION OF THE INVENTION As described above, the present invention relates to a bonding layer formed on a substrate or an elastic body, a tip formed on the bonding layer, and a hollow surrounded by the bonding layer and the tip. Area, a probe for detecting a microcurrent or a microforce having a micro tip main material is a metal, and its surface is a metal oxide film, characterized in that, The above-described object of the present invention can be achieved. Hereinafter, details of the manufacturing method will be described with reference to the drawings. FIG. 1 is a sectional view showing the manufacturing process. First, the concave portion 3 is formed on the surface of the first substrate 1 made of silicon. For this, first, a protective layer 2 is formed on the first substrate 1, and then a desired portion of the protective layer 2 is patterned by photolithography and etching to expose a part of silicon. Etching the silicon using anisotropic etching or the like
Is used. As the protective layer 2, silicon dioxide or silicon nitride can be used. For etching silicon, it is preferable to use crystal axis anisotropic etching capable of forming a tip end portion sharply. By using an aqueous solution of potassium hydroxide or the like as an etchant, an inverted pyramid-shaped concave portion 3 surrounded by four surfaces equivalent to the (111) plane can be formed (see FIG. 1A).

Second, the protective layer 2 on the surface of the first substrate 1 is removed, and a release layer 4 is formed. In the step after the formation of the release layer 4, the material of the microtip 5 is formed on the release layer 4, and then the microtip 5 is separated from the release layer 4. You have to choose. That is, the material of the release layer 4 needs to have low reactivity and adhesion with the material of the tip 5. In particular, the first
When silicon is used for the substrate 1, a thermal oxidation furnace is used to thermally oxidize the silicon surface to easily and easily form the release layer 4 made of silicon dioxide (SiO ₂ ) with good reproducibility and controllability.
And the first substrate recess can be sharpened.

Third, a microtip 5 is formed on the release layer 4 including the concave portion. A vacuum deposition method, a sputtering method, or the like, which is a known thin film manufacturing technique, is used for forming the material of the microtip 5. After forming the film, the material of the microtip 5 is patterned using a known photolithography technique,
This is a minute tip (see FIG. 1C). The configuration and material of the microtip 5 are selected according to the purpose. In the case of the present invention, it is necessary to select a configuration and a material that can apply a voltage to the sample or the recording medium and that does not easily deform the tip of the microtip 5 in contact scanning or high voltage application. That is, in the present invention, the tip main material 51 is a metal having conductivity, and the outermost surface of the tip is the surface oxide film 54. Examples of the metal which easily oxidizes the surface and forms a hard stable oxide by the surface oxidation include aluminum Al, titanium Ti, chromium Cr, nickel Ni, tin Sn, tantalum Ta, tungsten W, rhenium Re and the like. The conductivity of the oxide film is an insulator,
Unlike semiconductors and conductors, materials are selected according to the purpose. However, these metals have a relatively large bonding force with the peeling layer 4 and have a property of being hardly peeled in a pressure bonding step described later. Therefore, the present invention is characterized in that the bonding auxiliary layer 52 and / or the separation auxiliary layer 53 are provided in the fine tip forming process. That is, the joining auxiliary layer 52 is formed on the tip main material after the tip main material is deposited. The bonding auxiliary layer 52 is an intermediate layer between the bonding layer 7 and the tip main material. The bonding auxiliary layer 52 has excellent adhesion to these two layers, and reliably presses the fine tip. In addition, the release auxiliary layer 53 is formed on the release layer 4 before forming the tip main material. The peeling assist layer 53 is an intermediate layer between the tip main material 51 and the peeling layer 4, and is capable of reliably peeling a microtip by having excellent peelability from any of these.
As a material of the release assisting layer 53, a material having low reactivity with the release layer 4 is desirable. As a material of the joining auxiliary layer 52,
A material having high adhesion to the bonding layer 7 in press bonding is desirable. Au is excellent in both the separation auxiliary layer 53 and the bonding auxiliary layer 52.

Fourth, a bonding layer 7 is formed on the second substrate 8 or on an elastic body 9 such as a cantilever formed on the second substrate 8. The second substrate 8 and the elastic body 9 are members that support the microtip 5 via the bonding layer 7. The bonding layer 7 is for bonding the tips by pressure. If a metal is used for the microtips 5 and the bonding layer 7, they can be deformed by pressure to obtain a metal bond. Therefore,
As the material, a metal, particularly a metal having a high ductility and malleability, such as Au and Pt, is desirable. Note that the wiring 10 for extracting a minute current may be formed of the same material and the same layer as the bonding layer 7. Further, by disposing a micro tip at the tip of the elastic body, it can be used as an AFM probe. Cantilever (cantilever) as elastic body
And a torsion lever in which a thin film flat plate is supported by two torsion beams. As the material of the elastic body, a material having excellent mechanical properties and having a small residual stress when formed into a thin film is preferable. The elastic body may also have the function of an actuator.

Fifth, the material of the microtip 5 on the release layer 4 including the recess 3 is bonded to the bonding layer 7. For this purpose, an alignment device capable of holding each substrate by a vacuum chuck or the like is used, and the microtip 5 on the first substrate 1 and the bonding layer 7 on the second substrate 8 are aligned and opposed to / contact with each other. The microtip 5 and the bonding layer 7 are bonded (compressed) by applying a load (see FIG. 1D).

Sixth, peeling is performed at the interface between the peeling layer 4 and the material of the microtip 5, and the material of the microtip 5 is transferred onto the bonding layer 7. That is, the first substrate 1 and the second substrate 8 are separated from each other, so that the separation is performed at the interface between the separation layer 4 and the microtip 5. Seventh, the separation assisting layer 53 is removed. The method includes a method of removing the entire peeling layer by etching, and a method of removing only the peeling auxiliary layer at the distal end by a method such as voltage or load scanning by bringing the tip of the microtip into contact with the sample surface. Eighth, the surface of the tip main material is oxidized (see FIG. 1 (e)). For this, a method of heating in the atmosphere or in an oxygen atmosphere is usually used. With this method, a thin oxide film can be reliably formed with good control. For example, when an oxide film is deposited on the surface by a sputtering method or the like, the tip tip shape is governed by the shape of the sputtered particles. Therefore, the tip tip shape sharpened by thermal oxidation of the first substrate cannot be preserved. According to this method, the shape of the concave portion of the first substrate can be made almost the same as the tip shape of the minute tip. In addition, it is stable against chemical changes, has a high melting point, and is hardly worn. It also has the effect of suppressing excess current from flowing between the tip and the medium. In addition, some metals have rectification characteristics due to bonding with an oxide film, and by using this metal, a probe that prevents overcurrent in reverse bias and is advantageous for detecting weak current in forward bias Can be provided.

[0014]

Embodiments of the present invention will be described below. [Example 1] Example 1 is a first embodiment of the present invention.
1 is a diagram illustrating a configuration of an M probe and a method of manufacturing the same.
FIG. 2 shows the configuration of the probe. The microtip 5 is joined on the joining layer 7 formed on the substrate. The wiring 10 is connected to the bonding layer 7. FIG. 1 is a cross-sectional view showing a process of manufacturing the probe of this embodiment. Hereinafter, the manufacturing method will be described with reference to FIG. First, a single crystal silicon wafer having a plane orientation (100) was prepared as the first substrate 1. Next, a silicon thermal oxide film having a thickness of 100 nm was formed as the protective layer 2. Next, a desired portion of the protective layer 2 was patterned by photolithography and etching to expose 4 μm square silicon. Next, the silicon in the patterning portion was etched by crystal axis anisotropic etching using an aqueous potassium hydroxide solution. The etching conditions were as follows: a 30% aqueous solution of potassium hydroxide was used;
The etching time was 10 minutes. At this time, an inverted pyramid-shaped concave portion 3 having a depth of about 3 μm surrounded by four planes equivalent to the (111) plane was formed (see FIG. 1A).

Next, the thermal oxide film as the protective layer 2 is coated with a mixed aqueous solution of hydrofluoric acid and ammonium fluoride (HF: NH ₄ F =
1: 5). Next, the first substrate 1 was cleaned using a mixed solution of sulfuric acid and hydrogen peroxide heated to 120 ° C. and a 2% aqueous hydrofluoric acid solution. Next, using an oxidation furnace, the first substrate 1 was heated to 1000 ° C. in an atmosphere of oxygen and hydrogen to deposit 400 nm of silicon dioxide as the release layer 4 (see FIG. 1B). Next, a portion to be the micro tip 5 is manufactured. First, 100 nm of rhenium Re was deposited as a tip main material 51 by a sputtering method. Next, 200 nm of gold Au was deposited as a bonding auxiliary layer 52 by a sputtering method. Next, the tip main material 51 and the joining auxiliary layer 52 were patterned by photolithography and dry etching using SF ₆ gas and BCl ₃ gas to form a micro tip 5.

Next, a silicon substrate on which a surface oxide film has been formed is prepared as the second substrate 8, and 5 n
m, Au are formed by a 300 nm vacuum evaporation method, and a pattern is formed by photolithography and etching.
The bonding layer 7 and the wiring 10 were used. Next, the microtip 5 on the first substrate 1 and the bonding layer 7 on the second substrate 8 are aligned and opposed to each other and contacted with each other. (Figure 1)
(D)). Next, the first substrate 1 and the second substrate 8 were separated from each other, so that the separation was performed at the interface between the separation layer 4 and the microtip 5. At this time, the height of the tip from the substrate surface was about 3 μm. The radius of curvature at the tip of the tip was about 30 nm. Next, the tip is placed in an oxygen atmosphere for 20 minutes.
Annealing was performed at 0 ° C., and a rhenium oxide layer was formed on the tip surface to form a surface oxide film 54 (see FIG. 1E).

FIG. 3 is a block diagram of an STM device to which a micro tip according to this embodiment is applied. In FIG. 3, a bias voltage is applied between the minute tip 5 and the sample 11, a tunnel current It flowing between the tip 5 and the sample 11 is detected, feedback is performed so that It is constant, and the Z direction of the XYZ drive piezo element 12 is changed. The distance between the tip 5 and the sample 11 is kept constant by driving. Further, the XYZ drive piezo element 12
ST, which is a two-dimensional image of the sample,
An M image is observed. Using this apparatus, a pulse voltage of 10 V and 3 μs was applied 100,000 times while scanning the microtip in the sample surface within the sample surface, and the tip shape was observed. As a result, no change in the shape was observed. Further, no change was observed in the shape of the recording bit due to the change in conductivity formed by the number of pulse applications. When this is compared with an experiment in which pulse application was similarly performed using a tip having a surface made of platinum Pt, a clear change in the tip shape was observed in the case of Pt. Further, the shape of the recording bit changed with the number of times.

[Embodiment 2] In Embodiment 2, a cantilever probe for AFM / STM according to a second embodiment of the present invention and a method for manufacturing the same are constructed. FIG. 5 shows the configuration of the probe. The microtip 5 is bonded on the bonding layer 7 formed on the cantilever 9. FIG. 4 is a cross-sectional view showing a manufacturing process of the probe of this embodiment. Hereinafter, the manufacturing method will be described with reference to FIG. First, the plane orientation (10
0) was prepared as the first substrate 1. Next, a silicon thermal oxide film is formed as a protective layer 2 by 100 n.
m was formed. Next, a desired portion of the protective layer 2 is patterned by photolithography and etching to a thickness of 4 μm.
Square silicon was exposed. Next, the silicon in the patterning portion was etched by crystal axis anisotropic etching using an aqueous potassium hydroxide solution. The etching conditions were as follows: a 30% aqueous solution of potassium hydroxide was used;
C. and the etching time was 10 minutes. At this time (11
1) An inverted pyramid-shaped concave portion 3 having a depth of about 3 μm surrounded by four surfaces equivalent to the surface was formed (see FIG. 4A).

Next, the thermal oxide film as the protective layer 2 is coated with a mixed aqueous solution of hydrofluoric acid and ammonium fluoride (HF: NH ₄ F =
1: 5). Next, the first substrate 1 was cleaned using a mixed solution of sulfuric acid and hydrogen peroxide heated to 120 ° C. and a 2% aqueous hydrofluoric acid solution. Next, using a thermal oxidation furnace, the first substrate 1 was heated to 1000 ° C. in an atmosphere of oxygen and hydrogen to deposit 400 nm of silicon dioxide as the release layer 4 (see FIG. 4B). Next, a portion to be the micro tip 5 is manufactured. First, 100 nm of rhenium Re was deposited as a tip main material 51 by a sputtering method.
Next, 200 nm of gold Au was deposited as a bonding auxiliary layer 52 by a sputtering method. Next, the tip main material 51 and the joining auxiliary layer 52 were patterned by photolithography and dry etching using SF ₆ gas and BCl ₃ gas to form a micro tip 5.

Next, a single crystal silicon substrate is prepared as the second substrate 8, and silicon dioxide 13 is added to both surfaces of the second substrate 8.
3 μm and 0.5 μm of silicon nitride 14 were formed. Next, the silicon nitride 14 on the surface was patterned into the shape of the cantilever 9 (cantilever) by photolithography and etching. At this time, the size of the cantilever is 50μ in width.
m and length 300 μm. Next, the silicon nitride 14 and silicon dioxide 13 on the back surface were similarly patterned into an etching mask shape. Next, 3 nm of titanium Ti,
Gold Au was deposited to a thickness of 50 nm, and a pattern was formed by photolithography and etching to form a bonding layer 7 and a wiring 10 on the cantilever. Next, the microtip 5 on the first substrate 1 and the bonding layer 7 on the second substrate 8 are aligned and opposed to each other and contacted with each other. (FIG. 4)
(D)). Next, the first substrate 1 and the second substrate 8 were separated from each other at the interface between the release layer 4 and the microtip 5 (see FIG. 4E). Next, a polyimide layer was applied as a surface protective layer 15 by spin coating and baked. Next, using the silicon nitride 14 on the back surface as an etching mask, the silicon substrate 8 was etched from the back surface with a 30% aqueous potassium hydroxide solution heated to 90 ° C. Next, the silicon dioxide layer 13 was removed with a mixed aqueous solution of hydrofluoric acid and ammonium fluoride. Finally, the surface protective layer was removed using oxygen plasma to form a cantilever probe. Next, the tip is placed in an oxygen atmosphere for 20 minutes.
A surface oxide film 54 was formed by forming a rhenium oxide layer on the tip surface by annealing at 0 ° C. (see FIG. 4F). Tip tip radius of curvature is about 30nm
Met.

FIG. 6 shows a block diagram of an optical lever type AFM / STM apparatus using the probe of this embodiment. AFM
The / STM apparatus comprises a probe consisting of a cantilever 9, a bonding layer 7, and a microtip 5 bonded to the bonding layer 7, a laser beam 61, a lens 62 for condensing the laser beam on the back surface of the bonding layer at the free end of the cantilever, and a cantilever. A position sensor 63 for detecting a change in the reflection angle of light due to the deflection displacement, a displacement detection circuit 66 for detecting displacement based on a signal from the position sensor, an XYZ axis driving piezo element 65, and an XYZ axis driving piezo element in the XYZ direction. And an XYZ driving driver 67 for driving the motor. A voltage application circuit 6 is provided between the microtip 5 and the sample 64.
A voltage is applied by 8, and a minute current It flowing between them is detected by a current detection circuit 69. Using this device,
By performing displacement detection and current detection while driving the XY of the XYZ drive piezo element 12, the unevenness of the sample and the conductivity
Two-dimensional images can be obtained at the same time. This AFM / STM
Using a device, the probe is brought close to a sample 64 made of a polyimide LB film formed on an electrode, and then the XYZ-axis driving piezo element 65 is driven in the X and Y directions while applying a bias voltage, so that unevenness on the sample surface is reduced. Conductivity could be observed. At this time, when a load of 5 × 10 ⁻⁸ N was applied and raster scanning at a scanning frequency of 10 Hz was repeated in an area of 2 μm square, the tip shape was observed. As a result, no change in the shape was observed. Comparing this with a similar experiment with a tip having a surface made of platinum Pt,
In the case of Pt, traces of wear were observed at the tip. After applying the above load and applying a pulse voltage of 10 V 3 μs 100,000 times while scanning the minute tip in the sample surface,
When the tip shape was observed, no change in shape was observed. Further, no change was observed in the shape of the recording bit due to the change in conductivity formed by the number of pulse applications. When this is compared with an experiment in which pulse application was similarly performed using a tip having a surface made of platinum Pt, P
In the case of t, a clear change is recognized in the tip shape. Further, the shape of the recording bit changed with the number of times.

[Embodiment 3] Embodiment 3 relates to an embodiment of A
The FM / STM probe has a configuration different from that of the second embodiment, and a method of manufacturing the same. The structure of the probe is the same as that of the second embodiment, and the manufacturing process of the probe is almost the same. FIG. 7 shows the manufacturing process of this embodiment. The differences from the second embodiment are the following. First, in the step of manufacturing a portion to be the microtip 5, first, the release assisting layer 5
As No. 3, a film of Au is formed to a thickness of 30 nm by a sputtering method, then, tungsten W is deposited as a tip main material 51 to a thickness of 100 nm by a sputtering method, and then gold Au is formed to a thickness of 200 nm as a bonding auxiliary layer 52 by a sputtering method.
Deposited. Next, the separation auxiliary layer 53, the tip main material 51 and the bonding auxiliary layer 52 are subjected to photolithography and SF ₆
A micro tip 5 was formed by patterning by dry etching using a gas and a BCl ₃ gas (FIG. 7C).
reference). Secondly, after the compression / peeling step, the peeling auxiliary layer 53 made of Au was removed by etching with a mixed aqueous solution of iodine and potassium iodide, as shown in FIG. Third, in the surface oxidation step, the tip was heated in air at 200 ° C. for 10 minutes to form a surface oxide film 54 made of a tungsten oxide layer (see FIG. 7F).

According to the above-mentioned manufacturing method, an AFM / STM probe having a minute tip composed of WO ₃ / W / Au could be provided. FIG. 6 using the probe of this embodiment.
An AFM / STM device similar to that described above was produced. This AFM /
Using an STM apparatus, the probe is brought close to a sample 64 made of a polyimide LB film formed on an electrode, and then the X of the XYZ axis driving piezo element 65 is applied while applying a bias voltage.
By driving in the Y direction, it was possible to observe irregularities and conductivity on the sample surface. At this time, when a load of 5 × 10 ⁻⁸ N was applied and raster scanning at a scanning frequency of 10 Hz was repeated in an area of 2 μm square, the tip shape was observed. As a result, no change in the shape was observed. Further, while applying the load described above and scanning the minute tip within the sample surface, 10 V
After a pulse voltage of 3 μs was applied 100,000 times, the shape of the tip was observed. As a result, no change in the shape was observed. Further, no change was observed in the shape of the recording bit due to the change in conductivity formed by the number of pulse applications.

[Embodiment 4] Embodiment 4 is an AF according to the present invention.
The M / STM probe has a configuration different from those of the second and third embodiments and a method of manufacturing the same. The configuration of the probe is the same as in Examples 2 and 3, and the manufacturing process of the probe is also the same as that shown in FIG. The differences from the third embodiment are the following. First, in a step of forming a portion to be the microtip 5, first, a 30 nm film of Au is formed as a peeling auxiliary layer 53 by a sputtering method, and then, a titanium film 100 nm is deposited as a tip main material 51 by a sputtering method. Next, 200 nm of gold Au was deposited as a bonding auxiliary layer 52 by a sputtering method. Next, photolithography and CF ₄ gas and BCl ₃
Patterned by dry etching using gas,
A minute tip 5 was formed (see FIG. 7C). Second
After the compression / peeling step, a peeling auxiliary layer 53 made of Au
FIG. 7E was removed by etching with a mixed aqueous solution of iodine and potassium iodide. Third, in the surface oxidation step, the tip was heated in air at 300 ° C. for 10 minutes to form a surface oxide film 54 made of a titanium oxide layer (see FIG. 7F).

According to the above manufacturing method, TiO ₂ / Ti / Au
An AFM / STM probe having a microtip consisting of the same was able to be provided.

An AFM / STM apparatus similar to that shown in FIG. 6 was manufactured using the probe of this embodiment. When the probe of this embodiment is used for recording and reproducing information, the rectifying property of the TiO ₂ / Ti junction can be used. First, by applying a pulse voltage of opposite polarity between the microtip and the recording medium at the time of information recording, it is possible to prevent an excessive current from flowing at the time of forming a recording bit. Also, at the time of information reproduction, a weak current can be detected by observing the current by the forward bias voltage. Using this AFM / STM apparatus, a probe is brought close to a sample 64 composed of a polyimide LB film formed on an electrode, and then XYZ is applied while applying a bias voltage.
By driving the axis driving piezo element 65 in the X and Y directions, it was possible to observe the unevenness and conductivity of the sample surface. At this time, when a load of 5 × 10 ⁻⁸ N was applied and raster scanning at a scanning frequency of 10 Hz was repeated in an area of 2 μm square, the tip shape was observed. As a result, no change in the shape was observed. After applying the above load and applying a pulse voltage of 10 V and 3 μs in the reverse direction of 100,000 times while scanning the minute tip in the sample surface, and observing the tip shape, no change in the shape was observed. Observation of the formed recording bit due to a change in conductivity by a forward bias showed no change in the bit due to the number of pulse applications.

[0027]

As described above, according to the present invention, it is not necessary to impart conductivity by sputtering or the like as a microtip, a uniform shape with good reproducibility is obtained, and the concave portion of the first substrate is sharpened. Since the shape can be made into the tip shape of the micro tip almost as it is, the tip can be formed sharply, and a method of manufacturing a micro tip or a probe that can easily make a plurality of tips (multiplication) can be provided. In addition, according to the present invention, the tip is chemically stable, the abrasion when scanning the microtip in contact with the sample is small, the tip of the microtip is hardly deformed by applying a high voltage, and excessive current is applied to the tip and the medium. A probe having a rectifying characteristic capable of providing a microtip or a probe having an effect of suppressing a flow between them, and suppressing an excessive current when applying a reverse bias voltage and detecting a weak current when applying a forward bias. Can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a method of manufacturing a probe according to a first embodiment.

FIG. 2 is a diagram showing a probe according to a first embodiment.

FIG. 3 is a block diagram of an STM device using a probe according to the first embodiment.

FIG. 4 is a diagram illustrating a method of manufacturing a probe according to a second embodiment.

FIG. 5 is a diagram showing a probe according to a second embodiment.

FIG. 6 is a block diagram of an AFM device using a probe according to a second embodiment.

FIG. 7 is a diagram illustrating a method of manufacturing a probe according to a third embodiment.

FIG. 8 is a cross-sectional view of a conventional process for manufacturing a microtip.

FIG. 9 is a cross-sectional view illustrating main steps of a conventional method for manufacturing a microtip.

FIG. 10 is a cross-sectional view illustrating a manufacturing process of a conventional microtip.

[Explanation of symbols]

 1: first substrate 2: protective layer 3: concave portion 4: release layer 5: microtip 7: bonding layer 8: second substrate 9: elastic body (cantilever) 10: wiring 11: sample 12: XYZ axis driven piezo element 13 : Silicon dioxide 14: silicon nitride 15: surface protective layer 51: tip main material 52: bonding auxiliary layer 53: peeling auxiliary layer 54: surface oxide film 61: laser beam 62: lens 63: position sensor 64: sample 65: XYZ axis Driving piezo element 66: Displacement detection circuit 67: XYZ driving driver 68: Voltage application circuit 69: Current detection circuit 201: Substrate 202: Thin film layer 203: Tip 204: Substrate 205: Resist 206: Resist opening 207: Conductive material 208: tip 510, 512: silicon dioxide 514: silicon wafer 518: pit 520 521: silicon nitride 522: pyramidal pit 532: Cr layer 534: Soukatto 540: Mounting block 542: metal film

Claims (16)

[Claims] 1. A substrate, a bonding layer made of metal formed on the substrate, a minute tip portion formed on the bonding layer, and a hollow region surrounded by the joining layer and the minute tip portion. Wherein the fine tip is mainly composed of a metal, and a metal oxide is formed on the surface of the fine tip. 2. The tip is made of a material whose main materials are aluminum Al, titanium Ti, vanadium V, and chromium C.
r, nickel Ni, zirconium Zr, niobium Nb, molybdenum Mo, tin Sn, hafnium Hf, tantalum T
2. The microtip according to claim 1, wherein the tip is any one of a, tungsten W, and rhenium Re. 3. A substrate, an elastic body formed on the substrate,
A micro-current or micro-force detecting device having a bonding layer made of a metal formed on the elastic body and having a micro tip portion and a hollow region surrounded by the micro tip portion and the bonding layer on the bonding layer; A probe provided with a microtip of the above, characterized in that the microtip is mainly composed of a metal and a metal oxide is formed on the surface thereof. 4. The tip is made of a material whose main material is aluminum Al, titanium Ti, vanadium V, chromium C
r, nickel Ni, zirconium Zr, niobium Nb, molybdenum Mo, tin Sn, hafnium Hf, tantalum T
4. The probe according to claim 3, wherein the probe is any one of a, tungsten W, and rhenium Re. 5. A method for manufacturing a microtip, comprising: (a) forming a concave portion on a surface of a first substrate; and (b) forming a release layer on the first substrate including the concave portion. (C) a step of forming a microtip of a metal as a main material on the release layer including the recess; (d) a step of forming a bonding layer on the second substrate; and (e) forming a recess of the first substrate. Bonding a microtip on the release layer including the bonding layer to the bonding layer on the second substrate; and (f) performing separation at an interface between the release layer and the microtip,
A step of transferring a microtip onto the bonding layer of the second substrate; and (g) a step of oxidizing the surface of the microtip transferred onto the bonding layer of the second substrate. Tip manufacturing method. 6. The tip is made of a material whose main material is aluminum Al, titanium Ti, vanadium V, and chromium C.
r, nickel Ni, zirconium Zr, niobium Nb, molybdenum Mo, tin Sn, hafnium Hf, tantalum T
The method according to claim 5, wherein the tip is any one of a, tungsten W, and rhenium Re. 7. The method according to claim 5, wherein, in the step (c), a bonding auxiliary layer is formed on the tip main material formed on the release layer in order to securely press the fine tip. A method for producing a microtip according to claim 6. 8. In the step (c), before forming the tip main material on the peeling layer, a peeling auxiliary layer is formed to surely peel off the fine tip, and the peeling auxiliary layer is formed in the step (g). The method for producing a microtip according to claim 5 or 6, wherein the auxiliary separation layer is removed beforehand. 9. In the step (c), a peeling auxiliary layer is formed to surely peel off the microtip before forming the tip main material on the peeling layer, and the peeling auxiliary layer is formed on the peeling layer. The bonding auxiliary layer is formed to securely press the microtip on the tip main material, and the peeling auxiliary layer is removed before the step (g). 3. The method for producing a microtip according to item 1. 10. A method according to claim 5, wherein a plurality of said recesses are formed on a surface of said first substrate, and a plurality of said microtips are formed on said second substrate. 2. The method for producing a microtip according to claim 1. 11. A method for manufacturing a probe for detecting a minute current or a minute force, comprising: (a) forming a concave portion on a surface of a first substrate; and (b) a release layer on the first substrate including the concave portion. (C) forming a microtip on a release layer including the concave portion; (d) forming an elastic material on a second substrate; and (e) forming an elastic material on the second substrate. Forming a bonding layer on an elastic material; (f) bonding a microtip on a release layer including a concave portion of the first substrate to a bonding layer on the second substrate; Peel off at the interface between the release layer and the microtip,
A step of transferring a microtip onto a bonding layer of an elastic material on the second substrate; (h) a step of forming an elastic body from the elastic material by removing a part of the second substrate; (i) Oxidizing a surface of the microtip transferred onto the bonding layer of the elastic body on the second substrate. 12. The tip is made of a material whose main material is aluminum Al, titanium Ti, vanadium V, chromium Cr, nickel Ni, zirconium Zr, niobium Nb,
The method according to claim 5, wherein the probe is any one of molybdenum (Mo), tin (Sn), hafnium (Hf), tantalum (Ta), tungsten (W), and rhenium (Re). 13. The method according to claim 11, wherein, in the step (c), a bonding auxiliary layer is formed on the tip main material formed on the release layer so as to securely press the fine tip. A method for manufacturing the probe according to claim 12. 14. In the step (c), before forming the tip main material on the peeling layer, a peeling auxiliary layer is formed to surely peel off the microtip, and the peeling auxiliary layer is formed in the step (i). 13. The method for manufacturing a probe according to claim 11, wherein the separation assisting layer is removed before the probe. 15. In the step (c), before forming the tip main material on the release layer, a release auxiliary layer is formed to surely release the microtip, and the release auxiliary layer is formed on the release layer. 13. The method according to claim 11, wherein a bonding auxiliary layer is formed to securely press the microtip on the tip main material, and the peeling auxiliary layer is removed before the step (i). 4. The method for producing a probe according to 1. 16. The semiconductor device according to claim 11, wherein a plurality of said recesses are formed on a surface of said first substrate, and a plurality of said microtips are formed on said second substrate. 2. The method for producing a microtip according to claim 1.